Treatment of hydrocarbon oils



Patented Aug. .30, 1932 UNITED STATES PATENT OFFICE SEYMOUR FERRIS, OFLANSDOWNE, PENNSYLVANIA, ASSIGNOR TO THE ATLANTIC v REFINING COMPANY, OFPHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA TREATMENT orHYDROCARBON OILS No Drawing.

The present invention relates to the art of mineral oil refining, andhas particular ref erence to the separation of crude petroleum orpetroleum products into fractions of different chemical compositionswhile of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products,'particularly oils 'of substantial viscosity, are separated into variousfractions by means of fractional extraction with an aromatic formate oracetate or mixture of aromatic formates and/or acetates, or mixture ofsolvents containing substantial quantities of aromatic formates and/oracetates.

It is recognized in the art that mineral oils, such as petroleum,comprise essentially a mixture of hydrocarbons of various groups orhomologous series of compounds, such for example, as parafiins of thegeneral formula C H olefines of the general formula C H hydroaromaticsand polymethylenes of the same empirical formula, and various otherseries of compounds of chain and/or ring structures in which thehydrogen to carbon ratio is less than in the foregoing series. A largenumber of individual compounds of each series and of differing boil ingpoints are present in petroleum.

The various types of crude petroleum, which are "(generally classifiedinto three groups, namely, paraflinic base, naphthenic q or asphalticbase, and mixed base, contain the various series of hydrocarbonsmentioned heretofore in different proportions. For example, in theparafiin base'crude oils, such as those obtained from the oil fields ofPennsylvania, there is a relatively high proportion of hydrocarbonshaving a chain structureand a high hydrogen to carbon ratio, whereas inthe naphthenic or a'sphaltic base crude oils, there is a relativelylarge proportion of hydrocarbons having ring structures and a lowhydrogen to carbon ratio. Mixed base crude oils, such' as are obtainedfrom the Mid-Continent oil fields, contain hydrocarbons "in proportionsintermediate these two extremes.

As the use of practically all of the petroleum oils is almost entirelyphysical, the above described chemical nature of those compared withanother.

Application filed May 15, 1931. Serial No. 537,751.

- oilsis important in reflecting certain physical characteristics.

naphthenic, and mixed base oils is evidenced by the physical propertiesof the various oils and particularly by the relationship of the specificgravity to the viscosity of one oil as For example, oil derived from aPennsylvania crude and having a viscosity of 400 seconds Sayboltuniversal at 100 F., will show a specific gravity at 60 F. of about0.878, whereas an oil of corresponding viscosity produced from anaphthenic crude, such as one from the Gulf coast area, will show a'specific gravity of about.0.933 at 60 F. The relationship between theviscosity and gravity indicates the degree of the paraflinic ornaphthenic character of the oil.

If a given crude petroleum be distilled into successive fractions andthe specific gravities and viscosities of the several fractions determined, it will be found that they conform to the generalrelationship:

0= log (V-38) in which G.is the specific gravity at F., V is Sayboltuniversal viscosity at 100 F., and a is a "constant known as theviscositygravity constant. Fractions from each of the different types ofcrude have different vis I cosity-gravity constants. Such constants arelower for fractions of the paraflinic crudes than are the constants forfractions of the naphthenic crudes. An article entitled Theviscosity-gravity constant of petroleum lubriin the formula and theviscosity-gravity constant of the fraction calculated, the constant willbe substantially the same for each of the several fractions of thecrude.

The viscosity gravity constants of the viscous fractions for some of-thetypical crudes,

are as follows:

These oils are increasingly paraflinic as the viscosity-gravityconstantsdecrease.

My invention is based upon the dlscovery that oils containing both theparaflinio series of hydrocarbons and the various naphthenic series maybe fractionally extracted with an aromatic formate or acetate. Phenylacetate is the selective solvent that I prefer to use, however, otheraromatic compounds such as toluyl formate may beemplo-yed, and areconsidered within the scope of my invention.

The Various series of hydrocarbons possess a differential solubility insuch solvents; the naphthenic hydrocarbons are much more soluble thereinthan the parafiinic hydrocarbons. I By meansof extraction with anaromatic formate or acetate, and more particularly with phenyl'acetate,it is, therefore, possible to effect a partial separation of thenaphthenic hydrocarbons from the para fiinic, and to obtain from an oilcontaining both classes of hydrocarbons, an oil which is much moreparaflinic than the original 'oil and one which is much more naphthenic.By my invention,

for example, it is possible to produce an oil of the qualityfiiormallyobtained from Appalachian .crudes, from crudes of the mixed ase typefrom the Mid-Continent area, and, conversely, to obtain oils from mixedbase crudes such as are normally obtained from the naphthenio oils ofthe Gulf coast area. 5

v In practicing my invention, I prefer tomix the oil fraction to betreated with a suitable proportion of an aromatic formate or acetate ormixture of them, and more particularly with phenyl acetate, at atemperature sufficiently high so that complete solution is effected anda homogeneous liquid obtained. I then cool the mixture to a temperaturesuiiL, ciently low to cause a separation of the liquid into a two-layersystem, the upper layer being a solution of a relatively small amount ofthearomatic formate'or acetate in the more araffinic portion of theoil,.and the lower thenic portion of the oil in the aromatic for:

. mate or acetate. Instead of this heating and cooling to effectextraction, I may simply agitate the mixture of liquids at normaltemperatures. Where substantial quantities of ayer comprising a solutionof the more naphand may cause it to be solid or semi-solid.

Separation of the two layers is then efiected matic formate oracetate,and repeat the process for an extraction of additional naphthenic bodiesfrom the oil.. The extraction may be repeated any desired number oftimes, thereby producing oils of progressively increasing paraffinicityas evidenced by a decreasing viscosity-gravity' constant. In waxbearingoils, the final undissolved product I is apmixture of solid and liquidhydrocarbons. While the exact chemical compositions of these compoundsare not known, it is probable that the' liquid hydrocarbons are branchedchain hydrocarbons of the paraffin series, whereas solid bodies arestraight chain paraffin hydrocarbons. This product may be-furtherseparated into solid and liquid hydrocarbons by any of the well-knowndewaxing processes, such as the cold settling process.

11 many instances it will be found of ad vantage to dewax the oil priorto' the extraction process, as this expedites the manual operation ofthe latter.

My invention will be further understood I from the following specificexample:

parts of a previously untreated distillate obtained from a Gulf coastcrude oil and having a viscosity of 61 2 seconds Saybolt,

universal at 100 VF, a specific gravity of 0.9303, and a consequentviscosity, gravity constant of 0.87 4 was mixed with 100 partsiof phenylacetate and heated to slightly above he temperature of completemiscibility, which in the particular case was approximately 50 C. Thehomogeneous liquid which resulted was cooled with agitation to 25 0.,and allowed to settle whereupon a two layer system formed, whichconsisted of an upper undissolved oil layer comprising 85 parts of themixture and a lower layer of oil dissolved in phenyl acetate comprisingapproximately parts of the mixture. After separation, the layers wereeach freed from phenyl acetate by vacuum distillation. The phenylacetate dissolved fraction yielded 82 parts of phenyl acetate and 33parts of oil phenyl acetate and, 67 parts of'an oil having having aviscosity of 73 seconds Saybolt uninndissolved fraction, oils may beobtained which are" increasingly paraflinic, as evidenced byprogressively decreasing viscositygravity constants.

It is evident that my process is practical 1y independent of theparticular nature or source of the crude oil, and that there may beproduced thereby oils of desired characteristics from oils which.heretofore have not been used as a source of oils of such desiredcharacteristics.

For example, my process maybe employed to produce from petroleum of amixed base type such as would, on normal batch distillation, give aresiduum with a viscosity of 150 seconds Saybolt universal at 210 F.with a specific gravity of 0.928 or more, a. lubricating stock with aviscosity of at 210 F. 150 seconds Saybolt universal, or more, and \aspecific gravity not higher than 0.910. This latter combination ofproperties is typical of cylinder stocks produced from Pennsylvaniacrudes.

In extracting oils containing appreciable amounts of wax, such oils maybe dewaxed, for example, by cold settling or centrifuging prior tocarrying out the extraction. My process is operable, however, in theabsence of preliminary dewaxing. Hereinabove, mixtures of solvents havebeen referred to. It is to be understood that in such mixtures the constituent solvents will not react with one another, nor with the oilupon which they are to be used, and that such mixtures will containsubstantial amounts of aromatic formates and/or acetates.

For brevity,'in the appended claims, the

"term aromatic acetate is employed in a generic sense to include one ora mixture of aromaticformates and/(Y acetates, or amixture of solventswhich contains substantial quantities of aromatic formates and/oracetates.

Also where herein and in the appended claims, an oil is specificallyreferred to as being viscous, it is to be understood that the oil is ofsubstantial viscosity, i. e., of the order of 50 seconds Sayboltuniversal at 100 F., or more.

What I claim is:

1. In the art oftrefining mineral oils, the process which comprisesseparating an oil containing parafiinic and naphthenic hydro-" carbonsinto fractions respectively richer in parafiinic and naphtheniccompounds by extracting said oil with an aromatic acetate.

2. In the art of-refining mineral oils, the

' lower layer.

process which comprises fractionally extracting an oil containingparaflinic and naphthenic hydrocarbons with an aromatic acetate toproduce fractions of the oil respectively richer in paraffinic andnaphthenic compounds.

3. In the art of refining mineral oils, the

process which comprises adding an aromatic acetate to an oil containingparaflinic and naphthenic hydrocarbons, heating the mixture to suchtemperature as to effect solution,

cooling the solution to form a two layer system, and separating theupper layer from the p 4. In the art of refining mineral oils, theprocess which comprises adding an aromatic acetateto an oil containingparaffinic and naphthenic hydrocarbons, heating the mixture to suchtemperature as to effect solution, cooling the solution to form a twolayer system, removing the lower layer, and similarly retreating theupper layer with an aromatic acetate.

5. In the art of refining mineral oils,the process which comprisesbringing a mineral oil containing paraffinic and naphthenic hydrocarbonsinto contact with an aromatic acetate, thereby to effect solution of aportion richer in naphthenic hydrocarbons in the aromatic acetate,separating the solution so formed from the remainder of the oil, andremoving the aromatic acetate from both portions of the oil, thereby toobtain fractions of the oil respectively richer in paraffinic andnaphthenic hydrocarbons.

6. The process for separating mineral oils containing paraflinic andnaphthenic hydrocarbons into fractions which comprises bringing the oilinto contact with an aromatic acetate, thereby to effect solution of aportion of the oil richer in naphthenic hydrocarbons in" the aromaticacetate, separating; the solution so formed from the remainder of theoil, and distilling the aromatic acetate from both of the portions ofthe oil, thereby to obtain fractions of the oil respectively richer inparaf-.

acetate, thereby partially dissolving the oil, separatinmthe phenylacetate solution of oil so treate and-removing the phenyl acetate fromthe treated oil.

9 The process of producing a lubricating stock of specific gravity lessthan .910 and of Saybolt universal viscosity greater than 150 seconds at210 F. from a crude petroleum which on-normal distillation yields aresiduumbf 150 seconds Saybolt universal viscosity at 210 F. and aspecific gravity greater than .928, which comprises producing a residuumfrom the crude petroleum, and extracting said residuum from said crudepetroleum with phenyl acetate.

10. In the art of refining mineral lubric-at: ing oil containingparaffinic and naphthenic hydrocarbons, the step of fractionallyextracting the oilwith phenyl acetate, to effect a separation offractions respectively richer in paraffinc and naphthenic compounds.

11. The process of producing a lubricating stock of specific gravityless than ,910 and of Saybolt universal'viscosity greater than 150seconds at 210 F. from a crude petroleum which on. normal distillationyields a residuum of 150 seconds Saybolt universal viscosity at 210 F.and a specific gravity of, greater than .928, which comprises separatinga residuum from said crude petroleum and bringing such residuum intocontact with phenyl acetate, to effect solution of a portion thereofwith phenyl acetate, separating the phenyl acetate solution of oil fromthe portion which does not disslove therein, and removing the phenylacetate from the oil of said solution. 12. In a process for separating aviscous miner oil containing paraflinicand naphthenic hydrocarbons intofractions which are respectively richer in naphthenic hydrocarbons andparaffinic hydrocarbons other; than wax, the step which comprisesextracting the oil with phenyl acetate.

13. In a process for separating viscous mineral oil liquid at ordinarytemperature containing .paraffinic and naphthenic hydrocarbons intofractions respectively richer in paraflinic and naphthenic hydrocarbons,the step which comprises extractingthe oil with phenyl acetate.

14. In a process for separating a substantially wax free viscous mineraloilv containing paraffinic and naphthenic hydrocarbons into fractionsrespectively richer in paraffinic and naphthenic hydrocarbons, the stepwhich tionofa mixed base crude oil to procure a. fraction having thequality of a corresponding fraction of a paraflinicbase crude, whichcomprises extracting the viscous fraction with phenyl acetate, andseparating the oil so treated into portions respectively richer inparaffinic and naphthenic compoundsl v 17. In the art of refiningmineral oils, the process which comprises adding phenyl acetate to aviscous oil liquid at ordinary temperatures containing parafiinic andnaphthenic hydrocarbons, heating the mixture to a temperature sufficientto effect solution, cooling the solution to a temperature sufficient toform two layers respectively richer in naphthenic hydrocarbons andparaflinic hydrocarbons other than wax, and separating the upper layersricher in paraffinic hydrocarbons from the lower layer richer innaphthenic hydrocarbons.

18. In the art of refining mineral oils, the process which comprisesadding phenyl acetate to a viscous oil liquid at ordinary temperaturescontaining paraflinic and naphthenic hydrocarbons, perature sufficientto effect solution, cooling the solution to a temperature sufficient toform two layers, separating phenyl acetate and paraffin wax from theupper layer, and separating phenyl acetate from the'lower layer toproduce one fraction richer in parafiinic and a second fraction richerin naphthenic hydrocarbons than said viscous oil.

In testimony whereof I affix my signature.

SEYMOUR W. FERRIS.

comprises extracting the oil with phenyl acetate.

15. The process oftreating a viscous fraction of a crude oil of one typecontaining paraffinic and naphthenic hydrocarbons to procure a fractionhaving the quality of a corresponding fraction of a crude oil ofdifferent type having a greater content of paraflinic hydrocarbons,which comprises extracting the viscousfraction with phenyl acetate, andseparating theoil so treated into portions respectively richer inparaflinic and naphthenic hydrocarbons.

16. The process of treating a viscous fracheating the mixture to a tern-

